During surgery it is necessary to locate a particular anatomic structure. This is often done by creating an incision through the skin and directly observing the structure. In some situations it is possible to advance a small tube or catheter into the structure of interest from a remote location such as through a vessel, cavity, or duct.
Light-emitting catheters have been used to produce an area of illumination on the surface of the body in order to locate a specific anatomical area. For example, U.S. Pat. No. 4,444,185 permits a tracheotomy by providing a device placed into a tracheal tube which emits outwardly directly light through the trachea and surrounding soft tissue as a means of locating the trachea. Also, in U.S. Pat. No. 5,540,691, a method and device are described for locating a hole in an intramedullary rod inserted into a long bone by observing illumination on the surface of the body provided by a light emitter placed within the intramedullary rod. U.S. Pat. No. 4,898,175 provides a method of observing images produced by light passed through body tissue to the surface. U.S. Pat. No. 5,423,321 presents a device a method for avoiding internal organs by placing a catheter which emits light along its length within the organ and placing a light sensor on the surgical tool and a means to indicate when light from the emitter is detected indicating proximity to the organ to be avoided.
However, none of the references cited above employ an array of sensors to precisely and accurately determine the direction of the emitter with respect to the sensor or to confirm precise and accurate centering over the emitter at low cost.
U.S. Pat. No. 5,423,321, “Detection of Anatomical Passages Using Infrared Emitting Catheter,” is a method for determining proximity to anatomical structure by placing a single emitter or line or line of emitters in structure and determining proximity to surgical instrument by measuring intensity of light emitted. U.S. Pat. No. 5,423,321 merely teaches the use of a single light sensor to serve as an indicating of the proximity of the emitter. It does not provide or suggest precise and accurate information on the direction of the emitter from the surgical tool. It does not have an array of sensors or emitters. It does not give direction of source from the emitter.
U.S. Pat. No. 5,540,691, “Optical Distal Targeting Method for an Intramedullary Nail,” is an apparatus for detecting the location of transverse holes of an intramedullary nail and aligning a drill with the holes. This system consists of a light source which is passed down the center of the intramedullary rod and a video system which is sensitive to infrared light which captures an image of the light transmitted through the transverse hole in the rod. The light simply shines out toward the surgeon who attempts to line up the drill by centering it on an area of light coming out of the hole. The infrared is visualized using either a video system sensitive to IR light or goggles which are sensitive to infrared. U.S. Pat. No. 5,540,691 requires the surgeon to wear night vision goggles or employ a video device which displays an image on a screen which shows the light transmitted through the tissue. There is no mechanism for automatically finding when the drill is accurately centered or oriented. The surgeon would need to divert his eyes to the video screen to judge when the light intensity was centered around the drill. Therefore, this system is much more difficult to use than the device of this invention. It would be much more difficult to accurately determine the center of a hole using the video system. The system and method of the invention is also much simpler and cheaper since one would not have to use a video system.